In general, a compressor is a mechanical apparatus that receives power from a power generation apparatus such as an electric motor, a turbine or the like and compresses air, refrigerant or various operation gases to raise a pressure. The compressor has been widely used in an electric home appliance such as a refrigerator and an air conditioner, or in the whole industry.
The compressor is roughly classified into a reciprocating compressor wherein a compression space to/from which an operation gas is sucked and discharged is defined between a piston and a cylinder, and the piston is linearly reciprocated inside the cylinder to compress refrigerant, a rotary compressor wherein a compression space to/from which an operation gas is sucked and discharged is defined between an eccentrically-rotated roller and a cylinder, and the roller is eccentrically rotated along an inner wall of the cylinder to compress refrigerant, and a scroll compressor wherein a compression space to/from which an operation gas is sucked and discharged is defined between an orbiting scroll and a fixed scroll, and the orbiting scroll is rotated along the fixed scroll to compress refrigerant.
Recently, a linear compressor has been developed among the reciprocating compressors. In the linear compressor, a piston is coupled directly to a linearly-reciprocated driving motor to prevent a mechanical loss by motion conversion, improve the compression efficiency and simplify the configuration.
FIG. 1 illustrates one example of a linear compressor. Normally, in the linear compressor, a piston 4 is linearly reciprocated inside a cylinder 2 by a linear motor 10 in a hermetic shell 1 so as to suck, compress and discharge refrigerant. The linear motor 10 includes an inner stator 12, an outer stator 14 and a permanent magnet 16. The permanent magnet 16 is linearly reciprocated between the inner stator 12 and the outer stator 14 due to a mutual electromagnetic force. As the permanent magnet 16 is driven in a state where it is coupled to the piston 4, the piston 4 is linearly reciprocated inside the cylinder 2 to suck, compress and discharge refrigerant.
In addition, the linear compressor includes a frame 3 on which the cylinder 2 is installed, and further includes a motor cover 5 bolt-coupled to the frame 3. The linear motor 10 is installed between the frame 3 and the motor cover 5. Moreover, a back cover 6 is installed on the motor cover 5, and a spring 7 is elastically supported between a member connected to the piston 4 and the back cover 6.
Hereinafter, in order to simplify a vibration system of the linear compressor, the cylinder 2, the piston 4, the frame 3, the motor cover 5, the back cover 6, the spring 7, the linear motor 10, a passage of refrigerant, and members used to compress the refrigerant are referred to as a linear compressor main body 20.
Generally, the compressor main body 20 is spaced apart from the bottom of the shell 1 to prevent vibration generated by the motion of the piston 4 from being transferred directly to the shell 1. The compressor main body 20 is supported by elastic members 9 to be spaced apart from the bottom of the shell 1. Normally, the number of the elastic members 9 is four. That is, one pair of elastic members 9 are installed at the front of the compressor main body 20, i.e., on the side of the frame 3, and the other pair of elastic members 9 are installed at the rear of the compressor main body 20, i.e., on the side of the back cover 6.
FIG. 2 is a schematic view illustrating the vibration system of the linear compressor.
A reaction force is imparted to the elastic members 9 due to the gravity of the compressor main body 20. A gravity center point G of the compressor main body 20 exists in a predetermined position inside the compressor main body 20. Accordingly, since installation points of the elastic members 9 are spaced apart from the gravity center point G of the compressor main body 20 by a predetermined distance r, a rotation moment is generated in the elastic members 9 due to the motion of the piston 4. When the elastic members 9 are vibrated due to the rotation moment, the compressor main body 20 supported by the elastic members 9 is vibrated. As a result, vibration and noise of the entire linear compressor are increased, and such vibration is transferred to a mount 30 for mounting the linear compressor on a system. Moreover, vibration is imparted to the system with the linear compressor mounted therein, so that vibration and noise of the system are increased.